Filter insert and method for producing the filter insert

ABSTRACT

The invention relates to a filter insert with a filtrate collecting chamber ( 4 ) which is connected to several filter bags ( 1 ) via a connecting plate ( 3 ). The connecting plate ( 3 ) includes longitudinal webs ( 5 ) for bridging joints ( 6 ) between the frames ( 14 ) of individual filter bags ( 1 ). The connecting plate ( 3 ) is sealingly welded to the filter bags ( 1 ) and the filtrate collecting chamber ( 4 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage of International applicationSer. No. PCT/DE 2009/001350 filed on Sep. 25, 2009, which claims benefitof priority to German Application Ser. No. 102008049865.3 filed on Oct.1, 2008, which is incorporated by reference herein.

TECHNICAL FIELD

The invention relates to a filter insert having a plurality of filterbags, a filtrate collecting chamber confining a filtrate collectingspace and enclosing several filter bags in a pot-shaped manner, afiltrate outlet of the filtrate collecting chamber and a frame of thefilter bags, wherein the frames of adjacent filter bags are sealinglyconnected to each other and the filtrate collecting chamber is sealinglyconnected to the filter bags. Further, the invention relates to a methodfor producing the filter insert.

BACKGROUND

A filter insert of the above specified kind is known for example fromEP1016449B1. In this filter insert the individual filter bags are sealedone against the other by means of cast resin. Connections of the filterbags are formed after hardening of the cast resin. As a result, thesealing of the filter bags one to the other is rather complex.

Further, it is known in the art to insert a heating wire betweenabutting edges of the frames of adjacent filter bags. The heating wireis energized and the frames of adjacent filter bags are welded together.The heating wire then remains in the filter insert. This configurationleads also to a huge effort for sealing the filter bags one against theother.

The leak tightness of the connection of the filter bags one against theother at the filtrate collecting space is, however, crucial for thiskind of filter insert, because at this very position the dirty sectionis separated from the clean section which comprises the filtratecollecting space. Since the filter insert mostly comprises a multitudeof filter bags the filtrate collecting space has a multitude of sealingpoints.

SUMMARY

It is an object of the invention to construct a filter insert of thekind specified above such that the filtrate collecting space is reliablysealed and that the effort for achieving the sealing is minimal. Inaddition, a method for producing the filter insert which is especiallysimple and cost-efficient in its application is to be established.

According to the invention the first problem is solved by the fact thatthe filtrate collecting chamber is sealingly connected to a connectingplate, that the connecting plate comprises several longitudinal webs andthat the longitudinal webs each connect frames of adjacent filter bags.

In this configuration the longitudinal webs of the connecting platebridge the frames of adjacent filter bags and ensure the sealing of thefilter bags one against the other. The connecting plate thus comprisesat least as many longitudinal webs as the filter insert according to theinvention has joints to be sealed between adjacent filter bags. In thiscase the longitudinal webs rest across the joints of adjacent filterbags. This results in a particularly large sealing area which comprisesalso a direction change in order to seal the frames one against theother and against the longitudinal webs. In this way the filtratecollecting chamber is especially reliably sealed.

The connecting plate contributes to a particularly high stability of thefilter insert according to the invention, if the longitudinal webs ofthe connecting plate bridge the butt joints between the frames ofadjacent filter bags. For this reason, mechanical loads on the filterbags will not lead to a defect in the liquid tightness of the filtratecollecting space.

A particularly reliable sealing of the filter bags one against the othercan easily be achieved in accordance with a further advantageousembodiment of the invention, if the frames of adjacent filter bags arewelded to the longitudinal webs of the connecting plate.

According to a further advantageous embodiment of the invention, thewelding of the frames to the connecting plate will result in a highstability and reliable tightness, if the welding of the frame to theconnecting plate is two-dimensional. The two-dimensional welding ispreferably produced in a mirror welding process wherein the surface ofthe interconnected frames which is to face the connecting plate and theconnecting plate itself are each partially melted by means of a weldingmirror. In the process of this partial melting the butt joints betweenthe frames are already fused with each other. After a subsequentpressing together of the partially melted surfaces of the frames and theconnecting plate the component parts are welded togethertwo-dimensionally. Forces acting between the frames of adjacent filterbags will be absorbed by the longitudinal webs of the connecting plate.Due to this configuration the filter insert according to the inventionhas a particularly high stability.

The filter insert according to the invention has a high stability, ifthe longitudinal webs of the connecting plate are connected to eachother by means of cross webs and if the cross webs and the longitudinalwebs delimit apertures for connecting channels of the frame with thefiltrate collecting space. Furthermore, the apertures ensure a reliableconnection of the channels with the filtrate collecting space so that,after the sealing connection of the connecting plate to the frame of thefilter bags is achieved, a simple visual check verifies theaccessibility of the individual channels of the filter bag frames.

The manufacture of the filter insert according to the invention isfurther simplified, if the filter bag frames and the connecting plateare made of the same thermoplastic material.

According to a further advantageous embodiment of the invention, asealing connection between the filtrate collecting chamber and theconnecting plate proves to be especially simple, if the filtratecollecting chamber or the collecting plate comprise a circumferentialgroove while the respective other member vis-à-vis comprises a lipengaging in the groove. In addition, this configuration enables areliable alignment of the filtrate collecting chamber in regard of theconnecting plate.

The lip of the filtrate collecting chamber or of the connecting platecould, for example, be glued in place in the groove of the respectiveother member vis-a-vis. According to a further embodiment of theinvention the sealing of the filtrate collecting space is simplified,however, if the groove and the lip of the filtrate collecting chamberand of the collecting plate are sealingly welded.

The second problem, namely the accomplishment of a method for producingthe aforementioned filter insert which is especially simple andcost-efficient in its application, is solved according to the presentinvention by frames of adjacent filter bags which are partially meltedin a two-dimensional areas at their side facing the filtrate collectingspace and longitudinal webs of a connecting plate for a filtratecollecting chamber which are partially melted in two-dimensional areasand by pressing the partially melted component parts one against theother.

As a result of this configuration a butt joint between the frames ofadjacent filter bags is bridged by longitudinal webs of the connectingplate. The welding of the longitudinal webs with the frames covers thewhole of the surface of the longitudinal webs. Thus, the welding iscapable of absorbing high forces and ensures a reliable sealing of thefiltrate collecting space.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention allows a multitude of embodiments. For furtherclarification of its basic principle one of these embodiment isrepresented in the drawing and is described below, wherein

FIG. 1 shows a filter insert according to the invention in transversesection;

FIG. 2 depicts a sectional view cut through the filter insert of FIG. 1along the line II-II;

FIG. 3 is an enlarged sectional view of a sealing of a filtratecollecting space of the filter insert of FIG. 2 cut along the lineIII-III;

FIG. 4 shows an enlarged sectional view of a sealing of adjacent filterbags of FIG. 2 cut along the line IV-IV.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 shows a filter insert having a plurality of filter bags 1 and afiltrate collecting space 2. The filtrate collecting space 2 comprises apot-shaped filtrate collecting chamber 4 being sealingly connected witha connecting plate 3. Connecting plate 3 conjoins the filtratecollecting chamber 4 with the filter bags 1.

FIG. 2 shows a sectional view cut through the filtrate collectingchamber 4 of FIG. 1 along the line II-II. It can be seen that theconnecting plate 3 comprises a multitude of longitudinal webs 5. Thenumber of longitudinal webs 5 corresponds exactly to the number of buttjoints 6 of adjacent filter bags 1 which are depicted in FIG. 4. Thus,the filter insert has one filter bag 1 in excess of the number oflongitudinal webs 5. Furthermore, the longitudinal webs 5 areinterconnected by means of cross webs 7. The longitudinal webs 5 and thecross webs 7 delimit apertures 8 through which channels 9 of the filterbags 1 shown in FIG. 4 are connected with the filtrate collecting space2. The filtrate collecting chamber 4 comprises a connecting tube 10 fordischarging the filtered medium.

FIG. 3 shows in an enlarged sectional view cut along line III-III ofFIG. 2 the sealing connection of the filtrate collecting chamber 4 tothe connecting plate 3. It can be seen that the filtrate collectingchamber 4 comprises a circumferential groove 11 in which acircumferential lip 12 of the connecting plate 3 is welded. The filtratecollecting chamber 4 has several supporting webs 13 for guiding thefiltered medium. The supporting webs 13, moreover, reinforce thefiltrate collecting chamber 4. The filter bag 1 has a frame 14 which iswelded to the connecting plate 3.

FIG. 4 is an enlarged sectional view through the fixation of twoadjacent filter bags to the connecting plate 3. It can be seen that thefilter bags 1 comprise planar filter media 15. A space between theframes 14 and the filter media 15 is connected to the filtratecollecting space 2 by means of channel 9 passing through frame 14.Longitudinal web 5 of connecting plate 3 is welded over the butt joint 6of frame 14 of the adjacent filter bags 1.

For the manufacture of the filter insert the individual filter bags 1pre-fitted with the filter media 15 are at first arranged and the upperside of the frames 14 at the butt joints 6 is partially melted by meansof a welding mirror. Afterwards one side of the connecting plate 3 isalso partially melted by means of a welding mirror. The partially meltedareas of the filter bags 1 and of the connecting plate 3 are thenpressed against each other. After cooling down the groove 11 of thefiltrate collecting chamber 4 and lip 12 of the connecting plate 3 arepartially melted and pressed against each other. Thus, the componentparts of the filter insert are connected with each other and thefiltrate collecting space 2 is reliably sealed.

The invention claimed is:
 1. A filter insert having a space forcollecting a filtrate, the space being reliably sealed, the filterinsert comprising: a plurality of filter bags, each filter bag connectedto each of a plurality of frames, wherein the frames of adjacent filterbags are sealingly connected to each other; a filtrate collectingchamber sealingly connected to the filter bags and having a filtrateoutlet for removing collected filtrate from the filter insert, thefiltrate collecting chamber adapted to form a filtrate collecting spaceand adapted to enclose the filter bags in a pot-shaped manner; and aconnecting plate sealingly connected to the filtrate collecting chamber,the connecting plate comprising a plurality of longitudinal webs thatconnect the frames of adjacent filter bags to each other.
 2. The filterinsert of claim 1, wherein the longitudinal webs of the connecting platebridge butt joints between the frames of adjacent filter bags.
 3. Thefilter insert of claim 2, wherein the frames of adjacent filter bags arewelded to the longitudinal webs of the connecting plate.
 4. The filterinsert of claim 3, wherein the welding location of the frames and theconnecting plate is two-dimensional.
 5. The filter insert of claim 4,wherein the longitudinal webs of the connecting plate are interconnectedby cross webs and wherein the cross webs and the longitudinal websdelimit apertures for connecting channels of the frames and the filtratecollecting space.
 6. The filter insert of claim 5, wherein the frames ofthe filter bags and the connecting plate are made of the samethermoplastic material.
 7. The filter insert of claim 6, wherein thefiltrate collecting chamber or the connecting plate comprises acircumferential groove and wherein the respective other member comprisesa lip engaging in the groove.
 8. The filter insert of claim 7, whereinthe groove and the lip of the filtrate collecting chamber and theconnecting plate are sealingly welded.
 9. A method for producing afilter insert according to claim 1, comprising: partially melting in alaminary area the frames of adjacent filter bags at a side facing thefiltrate collecting space; partially melting in a laminary area thelongitudinal webs of the connecting plate sealingly connected to thefiltrate collecting chamber; and pressing the partially melted componentparts one against the other.